Internet DRAFT - draft-xia-mext-hioptv4

draft-xia-mext-hioptv4






Network Working Group                                             F. Xia
Internet-Draft                                               B. Sarikaya
Expires: July 14, 2012                                        Huawei USA
                                                        January 11, 2012


   DHCPv4 Options for Home Information Discovery in Dual Stack MIPv6
                     draft-xia-mext-hioptv4-04.txt

Abstract

   This document defines DHCPv4 options for dynamic discovery of home
   network information in Dual Stack Mobile IPv6.  New DHCPv4 options
   are defined which allow a mobile node to request the home agent
   IPv4/v6 address, FQDN, or home network prefix and obtain it via the
   DHCPv4 response.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on July 14, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Home Network Information Discovery Using DHCPv6  . . . . . . .  4
   4.  DHCPv4 options for HA Dynamic Discovery  . . . . . . . . . . .  4
     4.1.  Home Network Information Option  . . . . . . . . . . . . .  4
     4.2.  DSMIP6 DHCPv4 Relay Agent Option . . . . . . . . . . . . .  5
     4.3.  Common Sub-options . . . . . . . . . . . . . . . . . . . .  6
   5.  Appearance of the options  . . . . . . . . . . . . . . . . . .  8
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   7.  IANA considerations  . . . . . . . . . . . . . . . . . . . . .  8
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     9.2.  Informative References . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10


































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1.  Introduction

   Before a mobile node can exchange Mobile IPv6 signaling with a home
   agent (HA), it should either know the IP address of the home agent
   via pre-configuration, or dynamically discover it.  For dynamic
   discovery, new Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
   options are defined in [I-D.ietf-mip6-hiopt] which allow a mobile
   node to request the home agent IPv4/ IPv6 address, Fully Qualified
   Domain Name (FQDN), or home network prefix, collectively called home
   network information and obtain it via the DHCPv6 response.

   Mobile IPv6 Support for Dual Stack Hosts and Routers (DSMIPv6)
   extends Mobile IPv6 specification [RFC3775] to allow the registration
   of IPv4 addresses and the transport of packets over IPv4 tunnels
   between mobile nodes and home agents ([RFC5555]).  DSMIPv6 home
   agents are dual-stacked and can support IPv4 only mobile nodes.
   DSMIPv6 HA can support dual-stacked mobile nodes connected to the
   networks that are IPv4 only.  Mobile nodes can register their IPv4
   home and care-of addresses with HA and can tunnel IPv4 packets to the
   HA.

   With home network information discovery in DSMIPv6, there are
   actually four different cases:

   o  Discovering HA's IPv6 address with DHCPv6 for IPv6 only mobile
      nodes

   o  Discovering HA's IPv4 address with DHCPv6 for dual-stacked mobile
      nodes in IPv6 network

   o  Discovering HA's IPv4 address with DHCPv4 for IPv4 only mobile
      nodes

   o  Discovering HA's IPv6 address with DHCPv4 for dual-stacked mobile
      nodes in IPv4 network

   The first two cases are dealt with in [I-D.ietf-mip6-hiopt], while
   the last two cases are specified in this document.  DHCPv4 options
   are defined based on DHCPv4 protocol specified in [RFC2131].


2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].





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3.  Home Network Information Discovery Using DHCPv6

   The following DHCPv6 options and their sub-options are used for
   dynamic discovery of the home agent's IPv4/IPv6 address, IPv6 home
   network prefix, or FQDN information in DSMIPv6:

   Home Network Information Option

      This option allows the exchange of home network information
      between the mobile node (DHCPv6 client) and the DHCPv6 server.  It
      is used to indicate the target home network requested by the
      mobile node to the DHCPv6 server.  It also conveys the home
      network information assigned by the DHCPv6 server to the mobile
      node as a response.

   MIP6 Relay Agent Option

      This option carries the home network information for the mobile
      node from the DHCPv6 relay agent to the DHCPv6 server.  This is
      needed in case when the NAS is collocated with the DHCPv6 relay
      agent and the NAS gets the home network information from external
      AAA servers.  MIP6 Relay Agent option is added to DHCPv6 message
      when the NAS/DHCP relay agent relays DHCPv6 request message from
      the mobile node to the DHCPv6 server.  Being populated with this
      information, the DHCPv6 server uses Home Network Information
      Option to reply to the mobile node.

   Common Sub-options

      This sub-option is a container for a home network parameter in the
      Home Network Information option.


   In this document, Home Network Information Option and DSMIP6 DHCPv4
   Relay Agent Option for DHCPv4 are defined in Section 4.1 and
   Section 4.2, respectively.  These options carry the information such
   as IPv4 address of the dual-stacked home agent, IPv6 home network
   prefix, IPv6 home agent address, FQDN of HA and Home network
   identifier.  Common Sub-options are defined in Section 4.3.


4.   DHCPv4 options for HA Dynamic Discovery

4.1.  Home Network Information Option

   The option allows the exchange of home network information between
   the mobile node (DHCPv4 client) and the DHCPv4 server.  It is used to
   indicate the target home network requested by the mobile node to the



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   DHCPv4 server.  It also conveys the home network information assigned
   by the DHCPv4 server to the mobile node as a response.


         0                   1
         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |  option-code  | option-length |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |           Id-type             |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |         Sub-options           |
         |          ... ...              |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Option-code
              OPTION_DSMIP6_HNINF (TDB)

          Option-len
              Length of the 'options' field in octets;
              MUST be a multiple of four (4).

          Id-type
              The type of Home Network Information.

              0    Visited domain (local ASP)

              1    Target MSP

              2    No preference by the mobile node

          Sub-options
              A series of sub-options as defined in Section 4.3.


4.2.  DSMIP6 DHCPv4 Relay Agent Option

   This option carries the home network information for the mobile node
   from the DHCPv4 relay agent to the DHCPv4 server.












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         0                   1
         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |  option-code  | option-length |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |         Sub-options           |
         |          ... ...              |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Option-code
              OPTION_DSMIP6_RELAY (TBD)

          Option-len
              Length of the 'options' field in octets;
              MUST be a multiple of four (4).

          Sub-options
              A series of sub-options as defined in Section 4.3.


4.3.  Common Sub-options

   This sub-option is a container for a home network parameter in the
   Home Network Information option or in the DSMIP6 DHCPv4 Relay Agent
   option.


























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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Sub-opt-code         |          Sub-opt-len          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                    Home Network Parameter                     .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Sub-opt-code

              A 16-bit unsigned integer for the type of the following
              Home Network Parameter field. Possible values are:

                  0    Reserved

                  1    Home network identifier

                  2    IPv6 home network prefix

                  3    IPv6 home agent address

                  4    IPv4 address of the dual-stacked home agent

                  5    Home agent FQDN

                  6 .. (2^16-1) Reserved

          Sub-opt-len

              The length of the Home Network Parameter field in units
              of octets.

          Home Network Parameter

              The provided home network information according to the
              Sub-opt-code. This is encoded as specified below.


   Mobile node MUST set the Sub-opt-code to 1 in the requesting Home
   Network Information option.  Mobile node MUST NOT set the Sub-opt-
   code to any other value.  DHCPv4 Relay Agent or DHCP server MAY set
   the Sub-opt-code to 1, 2, 3, 4, and 5 as needed.

   When the Sub-opt-code is set to 1 in the request, the Home Network
   Parameter field MUST contain an identifier to specify the home
   network requested by the mobile node.  This field MUST be set in the



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   form of a FQDN [RFC1035], encoded as specified in Section 8 of
   [RFC3315].  This sub-option in the request SHOULD be copied into the
   Home Network Information option returned in the reply.

   When the Sub-opt-code is set to 2, the Home Network Parameter field
   MUST include the 8-bit Prefix-Len followed by the 128-bit IPv6 Home
   Network Prefix.  The Prefix-Len information indicates the number of
   leading bits in the IPv6 Home Network Prefix that are valid.  The
   IPv6 Home Network Prefix information may be used to allow the mobile
   node to determine whether the home agent information received via
   DHCPv6 corresponds to a home agent on-link or not.

   When the Sub-opt-code is set to 3, the Home Network Parameter field
   MUST contain the 128-bit IPv6 address of the home agent.

   When the Sub-opt-code is set to 4, the Home Network Parameter field
   MUST contain the 32-bit IPv4 address of the dual-stacked home agent.

   When the Sub-opt-code is set to 5, it MUST contain the FQDN of the
   home agent as described in Section 8 of [RFC3315].


5.  Appearance of the options

   The Home Network Information Option MUST NOT appear in any message
   other than the following messages: DHCPDISCOVER, DHCPOFFER,
   DHCPREQUEST, DHCPACK,DHCPINFORM.

   The DSMIP6 DHCPv4 Relay Agent Option MUST NOT appear in any message
   other than the following messages: DHCPDISCOVER, DHCPREQUEST,
   DHCPINFORM.


6.  Security Considerations

   The security considerations in [RFC2131] and [RFC2132]apply.  Special
   considerations in [I-D.ietf-mip6-hiopt] are also applicable.


7.  IANA considerations

   IANA is requested to assign the OPTION_DSMIP6_HNINF and
   OPTION_DSMIP6_RELAY Option Codes for DHCPv4 in the registry
   maintained.







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8.  Acknowledgements

   The authors are grateful to Tomek Mrugalski and Ted Lemon for their
   constructive comments that helped us improve the draft.


9.  References

9.1.  Normative References

   [RFC1981]  McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
              for IP version 6", RFC 1981, August 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, March 1997.

   [RFC2132]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
              Extensions", RFC 2132, March 1997.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

   [RFC3775]  Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
              in IPv6", RFC 3775, June 2004.

   [RFC5555]  Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
              Routers", RFC 5555, June 2009.

9.2.  Informative References

   [I-D.ietf-mip6-hiopt]
              Jang, H., Yegin, A., Chowdhury, K., and J. Choi, "DHCP
              Options for Home Information Discovery in MIPv6",
              draft-ietf-mip6-hiopt-17 (work in progress), May 2008.










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Authors' Addresses

   Frank Xia
   Huawei USA
   1700 Alma Dr. Suite 500
   Plano, TX  75075

   Phone: +1 972-509-5599
   Email: xiayangsong@huawei.com


   Behcet Sarikaya
   Huawei USA
   5340 Legacy Dr. Suite 175
   Plano, TX  75074

   Phone:
   Email: sarikaya@ieee.org

































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